This invention relates to hand guns for applying hot melt adhesive to a work surface.
At the present time there are available many different types of hand guns for supplying adhesive to a substrate. Some of these hand guns use solid cartridges or flexible ribbons of adhesive which is melted within the gun and dispensed from it. U.S. Pat. Nos. 3,587,930 and 3,281,576 are typical of these types of guns. In general, these cartridge or ribbon type of hand guns are suitable for applications which require small amounts of adhesive. For many hot melt applications though which require melting large amounts of hot melt material they are not satisfactory. Such relatively heavy duty work generally employs a pressurized source of molten material from which the material is supplied in liquid or molten form to the hand gun through a heated flexible hose. The heated flexible hose or conduit through which the adhesive is supplied is very stiff, heavy, and difficult to manipulate. Consequently, it is customary with such hose fed guns to rotatably mount the hand gun or dispenser upon the end of the hose and to connect the gun to the hose through the handle or through a conduit which enters the gun forwardly of the handle. U.S. Pat. No. 3,543,968 illustrates a typical gun in which hot melt adhesive is fed from a hose through the handle of the gun. U.S. Pat. Nos. 3,971,492 and 4,006,845 illustrate other guns in which the hose fed adhesive is fed from beneath the gun through a conduit spaced forwardly of the handle of the gun.
All of the hose fed hand guns of which we are aware require heaters to be mounted on the body of the gun so as to maintain the molten adhesive in the molten state within the gun. In the absence of any such heaters the adhesive would cool within the gun barrel and clog the gun. Those heaters require an electrical connection or electrical lead between the flexible hose and the heater of the gun. Those electrical leads or cords though extending between the non-rotatable flexible hose and the rotatable hand gun are subject to being damaged and in any event inhibit the rotary motion of the gun.
The prior art hose fed hand guns of which we are aware are also subject to criticism because of the difficulty of rotating the guns relative to the flexible hoses to which they are connected. The swivel design between the guns and the flexible hoses has heretofore been characterized by a very high friction component or drag between the gun and the flexible hose. This drag contributes materially to operator fatigue and inhibits use of the gun.